This wine is intended to be sweet.
The F pack likely was only a sweetener, with maybe some sorbate.
If it had a lot of sorbate in the F pack, the fermentation will likely start off very slowly, if at all. I guess the question is - is there a separate packet of sorbate that came with the kit?
If a separate packet, add it when instruction say to add it; after that, you likely will only have to sweeten the wine to taste.
If no separate packet of sorbate, you will have to get some sorbate to add for stabilizing. Add the sorbate, then sweeten to taste.
Once all these questons are answered and you make necessary adjustments, your wine will likely be just fine, so NO PANIC! All of us have had similar issues in our wine making.